Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Revenue recognition (Revenue Disaggregated) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 21, 2017	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Commodity sales	$ 66,531	$ 226,493	$ 233,150	$ 242,569
Transportation and processing	$ (2,034)	$ (9,503)	0	0
Gross commodity sales
Disaggregation of Revenue [Line Items]
Commodity sales			256,199	258,845
Oil
Disaggregation of Revenue [Line Items]
Commodity sales			173,555	171,749
Natural gas
Disaggregation of Revenue [Line Items]
Commodity sales			40,543	41,506
Natural gas liquids
Disaggregation of Revenue [Line Items]
Commodity sales			42,101	45,590
Transportation and processing
Disaggregation of Revenue [Line Items]
Transportation and processing			$ (23,049)	$ (16,276)